Near-eye display system

ABSTRACT

The present disclosure provides a near-eye display system for generating a virtual image of a display, including: a display, a first lens array comprising a plurality of concave microlenses having a first pitch, and a second lens array positioned in front of the first lens array, the second lens array comprising a plurality of convex microlenses having a second pitch, wherein the first lens array is positioned on an optical path between the display and the second lens array, and wherein the first lens array has a focal plane at the display and the second lens array has a focal plane at a virtual image plane of the first lens array.

CROSS REFERENCE TO RELATED APPLICATIONS

This Application is a continuation (and claims the benefit of priorityunder 35 U.S.C. § 120) of U.S. patent application Ser. No. 15/510,283,now U.S. Pat. No. 10,241,334 filed on Mar. 10, 2017, and entitledNEAR-EYE DISPLAY SYSTEM which is a National Stage application under 35U.S.C. 371 of International Application PCT/US2015/056296, filed on Oct.20, 2015, and entitled NEAR-EYE DISPLAY SYSTEM, which claims the benefitof priority to U.S. Provisional Patent Application No. 62/066,256 titled“NEAR-EYE DISPLAY SYSTEM” and filed on Oct. 20, 2014, the entirecontents of which are incorporated by reference herein, in theirentirety.

TECHNICAL FIELD

The present disclosure relates to a near-eye display system, which may,for example, be encompassed in a heads-up display system.

BACKGROUND

Head-Up Display (HUD) systems have become popular in a number ofapplications, including personal wearable devices. Generally, HUDsystems present data to a user without requiring the user to look awayfrom their usual viewpoints.

A near-eye display system creates a display in front of the user's fieldof vision and is an integral part of any HUD system. One of the limitingfactors in designing a near-eye system for HUD systems is the humaneye's accommodation. Accommodation is the process by which the human eyechanges optical power to maintain a clear image or focus on an object asits distance varies. A normal human eye can typically comfortably focuson objects at a distance of 25 cm or greater, although studies haveindicated that the minimum distance a normal human eye can focus(minimum amplitude of accommodation) can be as small as about 10Dioptre, which is roughly around 10 cm.

Wearable HUD systems are generally intended for ease of portability andcomfort of use. Compact systems that provide for the minimum amplitudeof accommodation of a user's eye, are desirable.

Improvements in near-eye displays are desirable.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the disclosure will become more apparentfrom the following description in which reference is made to theappended drawings wherein:

FIG. 1 is a schematic diagram of an example of a near-eye display (NED)system.

FIGS. 2A-H are a schematic diagrams of different arrangements and shapesof microlenses in a lens array.

FIG. 3 is a schematic diagram of an example of a lens array.

FIG. 4 is a schematic diagram of a near-eye display system, wherein thesolid line style (-) represent light rays, dashed and dotted lines (-▪ - ▪) represent the apparent path of light rays; and dashed-only lines(- -) represent the virtual image.

FIG. 5A is a schematic diagram of a spherical microlens surface.

FIG. 5B is a schematic diagram of an aspherical micolens surface.

FIG. 6A is a schematic diagram of a diffractive grating layer.

FIG. 6B is a schematic diagram of a Fresnel grooves layer.

FIG. 7 is a schematic diagram of an example of a folded-eye displaysystem.

FIG. 8 is a schematic diagram of another example of a folded-eye displaysystem.

FIG. 9 is a schematic diagram of an eyebox (shaded region) formed in anexample of a near-eye display system.

FIG. 10 is a schematic diagram of the results of a 2-D ray tracingsimulation of an example of a near-eye display system.

FIG. 11 is a process flow diagram for creating a virtual and real imagefrom a display for a near-eye display device.

DETAILED DESCRIPTION

Generally, the present disclosure provides a near-eye display (NED)system for generating a virtual image of a display, including: adisplay, a first lens array positioned in front of the display, thefirst lens array comprising a plurality of concave microlenses having afirst pitch, and a second lens array positioned in front of the firstlens array, the second lens array comprising a plurality of convexmicrolenses having a second pitch, wherein the first lens array has afocal plane at the display and the second lens array has a focal planeat a virtual image plane of the first array.

For simplicity and clarity of illustration, reference numerals may berepeated among the figures to indicate corresponding or analogouselements. Numerous details are set forth to provide an understanding ofthe examples described herein. The examples may be practiced withoutthese details. In other instances, well-known methods, procedures, andcomponents are not described in detail to avoid obscuring the examplesdescribed. The description is not to be considered as limited to thescope of the examples described herein.

A schematic illustration of an example near-eye display (NED) system 100is shown in FIG. 1. The near-eye display system 100 includes a display102 that transmits visual information for visual reception, and a firstlens array 104 and a second lens array 106 that transmit and refractlight provided by the display 102. FIG. 1 shows a convex first microlensarray 104 and a concave second lens array 106.

In the context of the present disclosure, it should be understood thateach of a lens' optical surfaces may be convex (bulging outwards fromthe lens), concave (depressed into the lens), or planar (flat). A lensis biconvex if both of its optical surfaces are convex, whereas a lensis biconcave if both of its optical surfaces are concave.

In the context of the present disclosure, a near-eye display system is asystem with one or more optical elements within the user's field ofvision that present an image for viewing by the user. The opticalelements may be transparent or opaque depending on the application. Forexample, as discussed further below in some embodiments, the displayitself may be within the user's field of vision, whereas in otherembodiments the display may be outside of the user's field of vision,and a beamsplitter, holographic optical element, or other opticalelement may be used to direct light from the display to the user's eye.

In the context of the present disclosure, the display 102 may be anydisplay that presents visual information by emitting light. An exampleof a display that may be used in the present disclosure is a liquidcrystal display (LCD).

In the context of the present disclosure, a lens array contains multiplesmall lenses, which may be referred to as microlenses. The microlensesof a lens array may be arranged in a one-dimensional or two-dimensionalmatrix. The examples disclosed herein contemplate lens arrays comprisingtwo-dimensional matrices of microlenses, which would typically be usedin conjunction with typical displays such as, for example, LCDs. Lensarrays comprising one-dimensional matrices of microlenses may be usefulin conjunction with retinal-scanning type near-eye displays.

In some embodiments, the microlenses of each lens array are all evenlyspaced. The term “pitch” is used to refer to the center-to-centerspacing between adjacent microlenses of an array.

The microlenses of an array may be formed from a block of transparentoptical material, or may be formed from transparent optical material ona supporting substrate. A supporting substrate may be a thin sheet oflight-permitting substrate. The optical material used for themicrolenses and/or the supporting substrate may, for example, be quartzglass, borosilicate glass (e.g. Pyrex™), or polymer-based materials suchas polydimethylsiloxane (PDMS) or poly(methyl methacrylate) (PMMA). Insome embodiments, a lens array may be made by preparing a mold and usingthe mold for example to stamp out the array from a suitable opticalmaterial, or filling the mold with suitable optical material.

In some embodiments, all microlenses in an array have the same focallength. Accordingly, each lens array may consist of either convex orconcave microlenses.

In the context of the present disclosure, it should be understood thattwo or more lens arrays, with different pitches, in series, collectivelyform a superlens. The pitch of a lens array is defined as the distancebetween the centers of adjacent microlenses in the lens array.

Microlenses of different shapes and arrangements in a microlens may beused, as desired. For example, FIG. 2A shows an example array 200A withcircular lenses 202A arranged in an orthogonal formation, and FIG. 2Bshows an example array 200B with circular lenses 202A arranged in ahexagonal formation. In both of the arrays 200A/200B, there is some“non-lens area” 204A/204B (formed by the gaps between microlenses), suchthat the “fill-factor” of the microlenses is less than 100%. Thehexagonal formation of circular lenses in array 200B has a higherfill-factor than the orthogonal formation circular lenses in array 200A.FIGS. 2C and 2D show example arrays 200C and 200D that provide 100%fill-factor, but the square microlenses 202C of array 200C of FIG. 2C,and the hexagonal microlenses 202C of array 200D of FIG. 2D may be moredifficult to fabricate than circular lenses.

Lens arrays with 100% fill factor provide increased light propagationefficiency in comparison to arrays with less than 100% fill factor. Forexample, where light from the display passes through gaps between themicrolenses, this light is not refracted and instead reaches the user'seye as stray light, which may be perceived as a blur, and result indecreased resolution. In some embodiments, the non-lens area of a lensarray may be covered with a light-blocking paint or other opaquematerial such that light is only permitted to pass through the lensportions of the lens array. In some embodiments, the non-lens areas ofboth of the first and second lens arrays 104/106 comprise opaquematerial. In some embodiments, the non-lens area of only one of thefirst and second lens arrays 104/106 comprises opaque material. Forexample, in some embodiments an opaque coating may be applied to thesecond (convex) lens array 106, which is the outermost array. In otherembodiments, an opaque coating may be applied to the first (concave)lens array 104, which may simplify fabrication since the first lensarray 104 has a flatter profile (e.g., the concave microlenses of thefirst lens array 104 may not protrude outwardly from the surface(s) ofthe array).

FIG. 2E shows an example lens array 200E with circular microlenses 202Earranged in an orthogonal formation, and separated from one another suchthat the edges of the microlenses do not abut each other, resulting in agreater percentage of non-lens area 204E (and thus a lower fill-factor)in comparison to array 200A of FIG. 2A. The non-lens area 204E of array200E is covered with a light-blocking material such that light can onlypass through the array 200E through the microlenses 202E.

Arrays such as the example array 200E of FIG. 2E with relatively greateramounts of non-lens area that is rendered opaque may be useful insituations where strong ambient light is present. For example, sunlightmanagement is an important consideration in the design of NEDs, becauseoftentimes sunlight can enter into the NED through the lens (e.g., byreflection from the user's cheek), if the intensity of the sunlightoverpowers the brightness of the display, it can wash out the display.By providing a lens array with a reduced fill factor and an opaquenon-lens area, the light-blocking coating on the non-lens area canadvantageously reduce the amount of sunlight entering the NED throughthe array.

The example arrays of FIGS. 2A-E have generally square shapes, but it isto be understood that the shape of a lens array can be varied dependingon the intended application. For example, lens arrays can have shapesthat are generally circular (e.g. array 200F of FIG. 2F), rectangular(e.g. array 200G of FIG. 2G), triangular (e.g. array 200H of FIG. 2H),hexagonal (now shown), or other shapes.

FIG. 3 is a schematic diagram of an example of a convex (second) lensarray 106 consisting of convex microlenses 108 having a pitch p 109.(The first lens array is not shown in FIG. 3.) In the context of thepresent disclosure, it should be understood that the relationshipbetween the pitches and focal lengths of the first and the second lensarrays 104 and 106, and the behavior of the light rays passing throughthe system 100, is defined by Equation 1:

$\begin{matrix}{{F = {\frac{p\; 1}{{p\; 1} - {p\; 2}}f\; 2}},} & {{Equation}\mspace{14mu} 1}\end{matrix}$wherein F is the focal length of the system 100 as a whole, p1 is thepitch of the first lens array 104, and p2 and f2 are the pitch andeffective focal length, respectively, of the second lens array 106.

In the context of the present disclosure, it should be understood thatfocal length is the measure of how strongly an optical system convergesor diverges light. For an optical system in air, it is the distance overwhich initially collimated rays are brought to a focus. The focal planeis the plane through a focal point and perpendicular to the optical axisof a lens. A virtual image is an image formed when the outgoing raysfrom a point on an object diverge and the image appears to be located atthe point of apparent divergence. In contrast, a real image is one thatis formed when the outgoing rays from a point on an object converge at areal location.

In some examples, particular combinations of pitch and focal lengths ofthe first and second lens arrays 104/106 may be selected such that thesuperlens can behave as a singlet lens producing a magnified image. Anillustration of a portion of an example of a near-eye display system 100is shown in FIG. 4. The display 102 is at the focal plane of the firstlens array 104. Outgoing rays from the display 102 diverge as they passthrough the first lens array 104, generating a virtual image 110 on thesame side of the first lens array 104 as the display 102, and arecollimated as they pass through the second lens array 106. In thisexample, the focal plane of the second lens array 106 is at the plane ofthe virtual image 110 generated by the first lens array 104.

In some embodiments, each microlens of each of the first and second lensarrays 104/106 is a spherical microlens. In the context of the presentdisclosure, it should be understood that a microlens is spherical whenthe microlens surface, at all points, is equidistant from the center ofthe microlens, as shown in FIG. 5A (e.g., the microlens has a constantradius of curvature. In other embodiments, the microlenses may beaspherical. In the context of the present disclosure, it should beunderstood that a microlens is a spherical when the points of themicrolens surface are not equidistant from the center of the microlens,as shown in FIG. 5B (e.g., the microlens does not have a constant radiusof curvature). Aspherical microlenses may be used for optical aberrationcorrection. Examples of optical aberrations include chromaticaberrations, distortion aberrations, coma aberrations and sphericalaberrations.

Chromatic aberrations can occur, for example, when color displays (suchas an LCD monitor) are viewed through a typical magnifying glass, andcolor separation might be observed. This is because the refractive powerof the magnifying glass is different for different colors (wavelengths).Usually chromatic aberrations are minimized with the use of lowrefractive index materials, or the surface of a lens can be treated withdiffractive gratings optimized for wavelengths of light of interest.Also, concave-convex lens pairs can be used such that they cancel outthe chromatic aberration. The concave and convex arrays 104 and 104 ofsystem 100 can be designed to minimize chromatic aberration.

Distortion aberrations can occur, for example, in typical sphericalmagnifiers, where the image viewed through the spherical magnifier canseem to be either pulled towards the viewer or away from the viewer atthe edges of the image. This is because the magnification differs as wemove from the center of the lens to the edge of the lens. This can becorrected by making the lens surface aspherical.

Other aberrations such as coma and spherical aberrations can also occurwith spherical lenses, since the effective resolution of the lens willbe far less than ideal because the light refracted by a spherical lensdo not actually get focused at a common point on the optical axis.Instead, the focal point would be spread over a certain range on theoptical axis, and the lens will never be in a perfect focus, which coulddecrease the resolution. This can also be corrected by having anaspherical lens surface. In practice, all non-ideal lenses cause opticalaberrations to occur to a certain degree, and can be challenging tocorrect for all of the aberrations at the same time. Prior art solutionstypically address aberrations through the use of additional lenses. Incontrast, system 100 comprises only two arrays 104 and 106 ofmicrolenses, and surface treatments may be used to correct foraberrations, such as for example, using diffractive gratings ormodifying the lens surface geometry from spherical to aspherical.Whether or not particular aspherical microlenses and/or surfacetreatments are desirable for a particular NED system depends on whattype of optical aberrations are required to be corrected. In someembodiments, a NED system design may begin with spherical microlenses inthe arrays, then, based on other elements of the system (e.g., whetherit is a folded or non-folded type system), adjust one or both of thelens arrays to include aspherical microlenses, diffractive gratings, orother surface treatments to address any optical aberrations.

In some embodiments, instead of each microlens of each being implementeda small simple lens, one or both of the first and second lens arrays104/106 may be implemented as an array of diffractive gratingmicrolenses or an array of Fresnel microlenses. A diffractive grating isan optical component with periodic structure, which splits and diffractslight into several beams traveling in different directions. Thedirections of these beams depend on the spacing of the grating and thewavelength of light.

FIG. 6A shows an example lens array 600A comprising a plurality ofdiffractive grating microlenses 602A. A diffractive grating microlensmay be configured to act as a convex microlens or a concave microlens.In the example of FIG. 6A, the lens array 600A has binary phase gratings(i.e., only 1 grating step size), but other grating types may be used inother embodiments. Also, in some embodiments diffractive optics can alsobe used in conjunction with refractive optics, for example a refractivelens can be surface treated to have diffractive gratings on it.

FIG. 6B shows an example lens array 600B comprising a plurality ofFresnel microlenses 602B. Each Fresnel microlens comprises a pluralityFresnel grooves that have the same curvature as corresponding portionsof a traditional continuous lens surface. In the example of FIG. 6B, thelens array 600B comprises convex Fresnel microlenses 602B, but concaveFresnel microlenses may be used to implement a concave lens array.

Some embodiments of a NED system according to the present disclosurecomprise lens arrays with aspheric microlenses having diffractivegratings formed on the surfaces of the microlenses. Such a lens arraymay require more initial time or effort to construct (e.g. a morecomplex mold may be required), but once the initial lens array design iscompleted mass production of such arrays would be largely similar toarrays with spherical microlenses (e.g., by using the mold for stampingthe arrays from suitable optical material).

In some embodiments, the near-eye display system may have a non-foldedconfiguration, such as in the example schematically depicted in FIG. 1.In other examples, the near-eye display system may be in a foldedconfiguration, as shown for example in FIGS. 7 and 8. In the context ofthe present disclosure, it should be understood that a non-folded opticsconfiguration is an optical system in which the display surface and thesurfaces of the lens arrays are parallel and share the same opticalaxis, which is normal to the surfaces. A folded optics configuration isan optical system in which the beam is bent for the purpose of reducingthe physical length of the system or for the purpose of changing thepath of the optical axis. Components such as free-form surface prisms,beam splitters, mirrors, waveguides and other optical components may beused to make a folded near-eye display system.

FIG. 7 shows one example of a folded near-eye display system 700 wherethe lens arrays 104/106 are the final elements that light from thedisplay passes through before reaching a user's eye. Briefly, the beamfrom the display 102 is redirected by a transparent beam redirectionelement 702 (e.g., a beam splitter, holographic optical element, or thelike) before it travels to the lens arrays 104/106, then to a user'seye. A null lens 704 is used to negate the optical effect of the lensarrays 104/106, thus allowing the outside scenery to be seen through thetransparent beam redirection element 702.

FIG. 8 shows a second example of a folded near-eye display system 800where the lens arrays 104/106 are the initial elements that light fromthe display passes through. Briefly, a beam from the display 102 travelsto the lens arrays 104/106 before it is redirected by a transparent beamredirection element 802, then to a user's eye. The transparent beamredirection element 802 may, for example, be embedded within atransparent optical medium between a rear surface 804 and a frontsurface 806.

Head-up display (HUD) systems were initially developed for militaryaviation, but are now used in commercial aircrafts, automobiles,computer gaming and wearable devices. HUD systems, for example, includehead-mounted wearable display devices that have the capability ofreflecting projected images as well as allowing the user to see throughit. Ideally, wearable HUD systems should be as compact as possible sothat the user is comfortable wearing the system. Consequently, thedisplay of most contemporary wearable HUD systems are positioned asclose to the eye as possible to minimize the overall form-factor. Thedistance of a display from the eye may be referred to as “eye relief” ofthe display. For example, a near-eye display system as disclosed hereinmay be used to permit smaller eye relieve than certain prior art HUDsystems.

One consideration in the design of a HUD is the eyebox. The eyebox isthe three-dimensional space in front of a near-eye display within whichthe complete virtual image of the display can be viewed by a user's eye.The larger the eyebox, the more freedom of head movement the viewer haswhile still being able to view the complete virtual image. An example ofan eyebox 114 of a near-eye display system 100 according to certainembodiments of the present disclosure is shown in FIG. 9. The eyebox 114is formed in the space created by overlapping collimated beams. The sizeof the eyebox is determined by the size of the display 102 and lensarrays 104/106, and the angle α, which may be referred to as the “exitangle.” Angle α is defined as the angle between the optical axis 120 ofthe arrays 104/106, and light rays refracted from the outer edges (whichmay be referred to as “edge rays”) of the second lens array 106. Angle αis considered to have a negative value when the edge rays converge, asshown in FIG. 9, which occurs in a concave-convex system such as system100. In contrast, Angle α is considered to have a positive value insystems where the edge rays diverge.

In 2-D ray tracing simulations, the eyebox can be viewed as the areawhere collimated beams overlap, as shown in FIG. 10. The results of thesimulation show the deflection of collimated beams, launched fromdifferent locations on the display 102, and deflected when exiting fromthe near-eye display system 100, which consists of the first and secondlens arrays 104/106.

The field of view (FOV) of a near-eye display is a linear function ofthe size of the lens arrays. Consequently, in the examples herein,without any change in the lens array parameters (such as focal length ormicrolens diameter), a large FOV can be achieved by increasing thesurface area of the lens arrays 104/106. An F-number is the ratiobetween the focal length and the aperture diameter of a lens. In someexamples, the present disclosure provides a near-eye display system withan F-number of less than 1. For example, some embodiments provide a NEDsystem with lens arrays 104/106 having a combined focal length of about5.4 mm and an aperture diameter of about 12 mm, which translates to anF-number of about 0.45.

In some embodiments, the distance between the first lens array 104 andthe second lens array 106 may be about 10 mm or less. For example, insome embodiments the first and second lens arrays 104/106 may be incontact with each other. In some embodiments, the distance between thefirst lens array 104 and the display 102 may be between about 0 mm andabout 50 mm.

In some embodiments, the combined overall focal length of the first andsecond lens arrays 104/106 may be about 5 mm, the exit angle of thefirst and second lens arrays 104/106 may be about −14 degrees. In someembodiments, the first lens array 104 may have a pitch of about 260 μm,and the second lens array 106 may have a pitch of about 250 μm. In someembodiments, the first lens array 104 may have a pitch of about 280 μm,and the second lens array 106 may have a pitch of about 269 μm. As longas the ratio between pitches and the respective focal lengths of thefirst and second lens arrays 104/106 are kept constant, any pitches willwork for given overall system focal length and exit angle. In someexamples, the first lens array may have a focal length of about −400 μmand the second lens array may have a focal length of about 1020 μm.

FIG. 11 is a process flow diagram 1100 for generating a virtual image. Adisplay can emit light representing a displayed image (1102). A first,concave microlens array can receive the emitted light and refract thelight, which can create a virtual image between the display and thefirst, concave microlens (1104). A second, convex microlens array canreceive the refracted light, and refract the light to create real imageof the emitted light representing the displayed image (1106). In someembodiments, the refracted light from the second, convex microlens arraycan be redirected to change the location of the resulting real image. Insome embodiments, the displayed image can be redirected before reachingthe first, concave microlens array.

Aspects of the embodiments are directed to a near-eye display system forgenerating a virtual image of a display. The near-eye display system mayinclude a display, a first lens array comprising a plurality of concavemicrolenses having a first pitch; and a second lens array positioned infront of the first lens array, the second lens array comprising aplurality of convex microlenses having a second pitch. The first lensarray can be positioned on an optical path between the display and thesecond lens array. The first lens array has a focal plane at the displayand the second lens array has a focal plane at a virtual image plane ofthe first lens array.

Aspects of the embodiments are directed to a method for generating avirtual image. The method can include receiving, at a first, concavemicrolens array, light emitted from a display, generating a virtualimage based on the light emitted from the display at a location betweenthe display and the first, concave microlens array, receiving, at asecond, convex microlens array, the light transmitted from the first,concave microlens array, and generating a real image based on the lightemitted from the display with the second, convex microlens array.

Aspects of the embodiments are directed to a wearable apparatusconfigured to perform the method steps. Aspects of the embodiments aredirected to a near-eye display device that includes a display means, ameans for generating a real image, and a means for generating a virtualimage. In some embodiments, the near-eye display device also includesmeans for changing the direction of emitted light.

In some implementations of the embodiments, the pitch of the first lensarray is not equal to the pitch of the second lens array, such that thevirtual image is magnified.

In some implementations of the embodiments, virtual image is magnifiedin comparison to the display by a magnification factor of at least 1.

In some implementations of the embodiments, the distance between thefirst lens array and the second lens array is between about 0 mm andabout 10 mm.

In some implementations of the embodiments, the distance between thefirst lens array and the display is between about 0 mm and about 50 mm.

In some implementations of the embodiments, the distance between thefirst lens array and the second lens array is between about 0 mm andabout 10 mm, and the distance between the first lens array and thedisplay is between about 0 mm to about 50 mm.

In some implementations of the embodiments, wherein the first lens arrayhas a pitch of about 260 μm.

In some implementations of the embodiments, wherein the second lensarray has a pitch of about 250 μm.

In some implementations of the embodiments, the first lens array has apitch of about 260 μm and the second lens array has a pitch of about 250μm.

In some implementations of the embodiments, the first lens array has afocal length of about −400 μm.

In some implementations of the embodiments, the second lens array has afocal length of about 1020 μm.

In some implementations of the embodiments, the first lens array has afocal length of about −400 μm and the second lens array has a focallength of about 1020 μm.

In some implementations of the embodiments, the first and second lensarrays have an exit angle of about −14 degrees.

In some implementations of the embodiments, the first and second lensarrays have a ratio of combined focal length to aperture diameter ofless than 1.

In some implementations of the embodiments, the first and second lensarrays have a ratio of combined focal length to aperture diameter ofabout 0.5.

In some implementations of the embodiments, the display, the first lensarray and the second lens array have the same optical axis.

Some implementations of the near-eye display system may include atransparent beam redirection element; and a null lens. The display maybe positioned substantially perpendicular to the first and second lensarrays. The transparent beam redirection element may be positioned onthe optical path between the display and the first lens array, and thefirst and second lens arrays may be positioned between transparent beamredirection element and a user's eye. The null lens may be positioned onthe opposite side the transparent beam redirection element from thefirst and second lens arrays and the null lens may be configured tonegate the optical effect of the first and lens arrays.

Some implementations of the near-eye display system may include atransparent beam redirection element embedded within a transparentoptical medium. The transparent beam redirection element may bepositioned on the optical path between the second lens array and auser's eye.

In some implementations of the embodiments, the microlenses arespherical lenses.

In some implementations of the embodiments, the microlenses areaspherical lenses.

In some implementations of the embodiments, the near-eye display systemincludes diffractive gratings formed on the surfaces of the microlenses.

In some implementations of the embodiments, the near-eye display systemincludes diffractive gratings formed on the surfaces of the microlenses.

In some implementations of the embodiments, one of the first and secondlens arrays comprises diffractive grating microlenses.

In some implementations of the embodiments, one of the first and secondlens arrays comprises Fresnel microlenses.

In some implementations of the embodiments, the microlenses of the firstlens array are biconcave.

In some implementations of the embodiments, the microlenses of thesecond lens array are biconvex.

In some implementations of the embodiments, the microlenses of the firstlens array are biconcave and the microlenses of the second lens arrayare biconvex.

In some implementations of the embodiments, the microlenses of the firstand second lens arrays are square lenses or hexagonal lenses arranged toprovide a fill factor of substantially 100%.

In some implementations of the embodiments, the microlenses of the firstand second lens arrays are circular lenses arranged in an orthogonalarrangement.

In some implementations of the embodiments, the microlenses of the firstand second lens arrays are circular lenses arranged in a hexagonalarrangement.

In some implementations of the embodiments, a non-lens area of one ofthe first and second lens arrays comprises an opaque material.

In some implementations of the embodiments, a non-lens area of one ofthe first and second lens arrays comprises an opaque material.

The present disclosure may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive.

The invention claimed is:
 1. A near-eye display (NED) system forcollimating light into a user's eye while substantially maintaining theuser's field of view (FOV), the system comprising: a display; a firstmicrolens array comprising a plurality of microlenses having a firstpitch; and, a second microlens array positioned in front of the firstmicrolens array, the second microlens array comprising a plurality ofmicrolenses having a second pitch and configured to sit proximally tothe user's eye; wherein, the first microlens array is disposed in anoptical path between the display and the second microlens lens array;further wherein the first microlens array has a focal plane at thedisplay and the second microlens array has a focal plane at a virtualimage plane of the first microlens array.
 2. The near-eye display systemof claim 1, wherein the pitch of the first microlens array is not equalto the pitch of the second microlens array, such that the virtual imageis magnified.
 3. The near-eye display system of claim 1, wherein thedisplay, the first microlens array and the second microlens array havethe same optical axis.
 4. The near-eye display system of claim 1,wherein one of the first or second microlens arrays comprisesdiffractive grating microlenses.
 5. The near-eye display system of claim1, wherein one of the first or second microlens arrays comprises Fresnelmicrolenses.
 6. The near-eye display system of claim 1, wherein themicrolenses of the first microlens array are biconcave.
 7. The near-eyedisplay system of claim 1, wherein the microlenses of the secondmicrolens array are biconvex.
 8. The near-eye display system of claim 1,wherein the microlenses of the first and second microlens arrays arecircular microlenses arranged in an orthogonal arrangement.
 9. Thenear-eye display system of claim 1, wherein the microlenses of the firstand second microlens arrays are circular microlenses arranged in ahexagonal arrangement.
 10. The near-eye display system of claim 1,wherein a non-microlens area of one of the first or second microlensarrays comprises an opaque material.
 11. The near-eye display system ofclaim 1, wherein the pitch of the first microlens array is not equal tothe pitch of the second microlens array, such that the virtual image iscollimated.
 12. The near-eye display system of claim 11, wherein thesystem has a focal length between 5 mm and 9 mm.
 13. The near-eyedisplay system of claim 1, wherein arrangement of the first and secondmicrolens arrays are one of: one convex microlens array and one concavemicrolens array; two concave microlens arrays; and, two convex microlensarrays.
 14. The near-eye display system of claim 13, wherein thicknessof the first and second microlens arrays are between 2 mm and 4 mm. 15.A wearable apparatus for magnifying light into a user's eye whilesubstantially maintaining the user's field of view (FOV), the apparatuscomprising: a first microlens array comprising a plurality ofmicrolenses having a first pitch; and, a second microlens array disposedbetween the first microlens array and the user's eye, the secondmicrolens array comprising a plurality of microlenses having a secondpitch and configured to be disposed less than a distance from the user'seye, the distance being less than 10 cm; wherein, the apparatus isconfigured to generate a virtual image further away from the distance toeye so that the image can be comfortably viewed.
 16. The wearableapparatus of claim 15, wherein the pitch of the first microlens array isnot equal to the pitch of the second microlens array, such that thevirtual image is magnified.
 17. The wearable apparatus of claim 15,wherein the display, the first microlens array and the second microlensarray have the same optical axis.
 18. The wearable apparatus of claim15, wherein one of the first or second microlens arrays comprisesdiffractive grating microlenses.
 19. The wearable apparatus of claim 15,wherein one of the first or second microlens arrays comprises Fresnelmicrolenses.
 20. The wearable apparatus of claim 15, wherein themicrolenses of the first microlens array are biconcave.
 21. The wearableapparatus of claim 15, wherein the microlenses of the second microlensarray are biconvex.
 22. The wearable apparatus of claim 16, wherein thewearable apparatus has a focal length between 5 mm and 9 mm.
 23. Thewearable apparatus of claim 15, wherein the arrangement of the first andsecond microlens arrays are one of: one convex microlens array and oneconcave microlens array; two concave microlens arrays; and, two convexmicrolens arrays.
 24. The wearable apparatus of claim 23, whereinthickness of the first and second microlens arrays are between 2 mm and4 mm.
 25. The wearable apparatus of claim 15, further comprising adisplay and a beamsplitter, the beamsplitter disposed in an optical pathbetween the display and second microlens array and configured to reflectan image from the display to the first microlens array, at least inpart.
 26. A wearable near eye display (NED) for generating a virtualimage further away from a user's eye so that the image can becomfortably viewed by the user, the NED comprising: a first microlensarray comprising a plurality of microlenses having a first pitch; asecond microlens array positioned in front of the first lens array, thesecond microlens array comprising a plurality of microlenses having asecond pitch; a transparent beam redirection element; and, a display;wherein the display is positioned generally perpendicular to the firstand second microlens arrays; wherein the first microlens array ispositioned on an optical path between the display and the secondmicrolens array; and, further wherein, the transparent beam redirectionelement is positioned on the optical path between the display and thefirst microlens array and the first and second microlens arrays arepositioned between transparent beam redirection element and the user'seye.
 27. The wearable apparatus of claim 26, wherein the transparentbeam redirection element is embedded within a transparent opticalmedium, wherein the transparent beam redirection element is positionedon the optical path between the second microlens array and the user'seye.
 28. The wearable apparatus of claim 26, further comprising a nulllens which is positioned on the opposite side the transparent beamredirection element from the first and second microlens arrays and thenull lens is configured to negate the optical effect of the first andmicrolens arrays.